There’s a pretty easy test to see if Donna Tartt’s third novel, The Goldfinch, is for you. When confronted with an almost 800-page book, is your initial reaction: “If I dropped this on my foot, I could seriously do some damage,” or “Best. Spider-killing Weapon. Ever.”?

If so, there is plenty of terrific fiction this fall that clocks in under 500 pages, such as James McBride’s “The Good Lord Bird,” which also features an orphan and an avian metaphor.

But for those who like big, twisty books, “The Goldfinch” is a hefty delight.

Tartt proved she knew how to go big with her debut novel, 1992’s much-loved cult novel,“The Secret History,” in which cloistered Classics students at a New England college turn murderous. While she averages about one book a decade, those books are steeped in a rare kind of storytelling that a certain kind of reader (namely this one) can happily get lost in. Tartt’s books submerge you for the duration until you emerge, blinking, in the sunlight at the end, wondering how the laundry pile got so big and just how many meals you might have missed.

“The Goldfinch,” in which Tartt explores art and loss, takes its title from the favorite painting of 13-year-old Theo Decker’s mom. As the book opens Theo, having been suspended from school, is being taken by his mom to see Carel Fabritius’s miniature masterpiece (an actual painting belonging to a museum in The Hague).

“It was a small picture, the smallest in the exhibition and the simplest: a yellow finch, against a plain, pale, ground, chained to a perch by its twig of an ankle,” Theo says.

Fabritius, who was Rembrandt’s student and Vermeer’s teacher, died the same year he painted “The Goldfinch," killed when a gunpowder factory exploded in Delft in 1654. The explosion also destroyed most of his work: less than a dozen paintings remain, including the little bird on his perch.

“Even a child can see its dignity: thimble of bravery, all fluff and brittle bone. Not timid, not even hopeless, but steadfast and holding its place. Refusing to pull back from the world.”

Theo, however, is less struck by the art than by a red-haired girl visiting the museum with her uncle when an explosion rocks the museum, killing Theo’s lovely mother and destroying the life Theo would have had if she’d been there to oversee it. (“She cast a charmed theatrical light about her so that to see anything through her eyes was to see it in brighter colors than ordinary.”)

In the confusion after the terrorist attack, Theo first comforts the girl’s dying uncle, who gives him a signet ring and an address. Then, in a state of shock, the boy walks out of the museum with the painting.

The stolen artwork, which Theo hides over the course of years, serves as his talisman and also twists him into fits of guilt and terror that he’ll get caught.

“If our secrets define us, as opposed to the face we show to the world: then the painting was the secret that raised me above the surface of life and enabled me to know who I am.”

Although centered around a miniature, “The Goldfinch” has a more expansive geographical canvas than Tartt’s two previous works, stretching from New York to Las Vegas and then Amsterdam.

After a few months living with his geeky friend and his family of brittle New York blue-bloods, Theo starts finding a sense of normalcy. The Barbours are kind, in their chilly way. Mrs. Barbour champions Theo because he once defended her son, Andy, from bullies. As for sweet, socially inept Andy, he would be perfectly happy to have Theo stay forever, especially in lieu of his nightmarish older brother, Pratt.

The signet ring and the address with the green door turn out to belong to an antiques store in New York – one of those genteel places open “by appointment only” – whose kindly owner, James Hobart, provides a haven for Theo and takes him on as his informal apprentice. “Hobie lived and wafted like some great sea mammal in his own mild atmosphere, the dark brown of tea stains and tobacco, where every clock in the house said something different and time didn’t actually correspond to the standard measure but instead meandered along at its own sedate tick-tock, obeying the pace of his antique-crowded backwater, far from the factory-built, epoxy-glued version of the world.”

There, Theo also briefly reunites with the red-haired girl, Pippa, who is also traumatized by the attack.

Then Theo’s alcoholic dad, a former actor turned professional gambler who had abandoned both his son and his wife, shows up, gets rid of everything Theo’s mother left in their apartment, and whisks Theo off to a deserted suburb of Las Vegas, where even Domino’s won’t deliver. “My new room felt so bare and lonely that, after I unpacked my bags, I left the sliding door of the closet open so I could see my clothes hanging inside,” Theo says.

Theo is still desperately missing his mother. The pain crops up without warning, as when he can’t tell her when his dad takes his girlfriend, Xandra, to a Bon Jovi concert: “It seemed terrible that she would never know this hilarious fact,” he thinks.

“The Goldfinch” is most often described as Dickensian, which is an apt comparison, both for the big, entertaining plot and the orphan who gets swept along on adventures. Theo most reminded me of Pip in “Great Expectations” with his eccentric guardians, shadowy benefactor, and his tendency to mold himself after whatever stronger personality is in his life at the moment. Mrs. Barbour has a few echoes of Miss Havisham, and the red-haired girl, Pippa, serves as his unobtainable Estella.

However, his best and only friend in Las Vegas comes straight from “Oliver Twist.” Boris is a Ukrainian Artful Dodger with serious substance-abuse issues and a budding criminal genius. Boris provides most of the levity in “The Goldfinch” and is as terrific a character as he is appalling an influence on Theo, who, after his mom’s death, lacks any kind of center beyond the painting.

Boris nicknames Theo “Potter” (as in Harry Potter), for his naivete, but there is a certain amount of ironic humor when Boris tries to teach Theo to shoplift, since in this case, the student is the one who has already pulled off a multimillion-dollar art heist. And Theo isn’t so much innocent as traumatized, as Tartt shows him struggling with grief and post-traumatic stress disorder and self-medicating with alcohol and whatever pills Boris can supply.

“I was trying to have fun and be happy. You wanted to be dead. It’s different,” Boris notes later of their wild days in the desert.

If the first half of the novel is a coming-of-age story, the second is the reckoning as Theo gets pulled into the shadowy underworld of forgery, art thieves, and organized crime. Near the end, “The Goldfinch” shifts into thriller territory, with a few attendant implausibilities. But by that point, a reader is happy to follow Theo – who, like another Dickens character, most definitely is not the hero of his own life – wherever “The Goldfinch” flies.